1. Field of the Invention
The present invention relates to coverings for pipelines, and in particular to coverings which comprise a heat recoverable sheet or tape coated on its inner surface with a hot-melt adhesive comprising a blend of polyethylene alkyl acrylates, particularly for covering pre-polymeric coated or thermally insulated pipelines, or where the heat recoverable backing is a tape, for helically wrapping around bare metal pipe, or polymeric coating of a thermally insulated pipe.
2. Introduction to the Invention
Heat recoverable articles are well known. They are articles the dimensional configuration of which may be made substantially to change when subjected to heat treatment.
Usually these articles recover, on heating, towards an original shape from which they have previously been deformed but the term "heat recoverable" as used herein, also includes an article, which, on heating, adopts a new configuration, even if it has not been previously deformed. Examples of such heat recoverable articles based on polymeric sheet material are found in U.S. Pat. Nos. 2,027,962, 3,086,242, and 3,597,372. Heat recoverable articles based on fabrics are also known. Typically these comprise a recoverable fabric in conjunction with a polymeric matrix formed by laminating a polymeric material to one or both sides of the fabric to render it impervious. Examples are described in European Patent Publication Nos. 116,393, 117,026, and 116,392.
The use of a polyethylene alkyl acrylate on a heat recoverable sleeve for environmental protection, particularly of a cable splice, is described in European Patent Publication No. 330,480, which is the counterpart of U.S. Pat. No. 4,965,320. The entire disclosure of U.S. Pat. No. 4,965,320 is incorporated herein by reference.